Nanowire light emitting diodes (LED) are of increasing interest as an alternative to planar LEDs. In comparison with LEDs produced with conventional planar technology, nanowire LEDs offer unique properties due to the one-dimensional nature of the nanowires, improved flexibility in materials combinations due to less lattice matching restrictions and opportunities for processing on larger substrates.
U.S. Pat. No. 8,138,493 issued on Mar. 20, 2012, which is incorporated herein by reference in its entirety, notes that it is difficult to fabricate light emitting diodes in the infra-red to green wavelength region using conventional planar technology in the GaN system and these give much lower efficiency than blue color emitting LEDs. This can be attributed to that: a) a miscibility gap for an InGaN material in the red and green wavelength region since InxGa1-xN with approximately 0.4<x<0.8 is not theoretically expected to be a stable material; and b) the high inherent defect density of the planar layers of the LED structure reduces photonic recombination efficiency by a much higher degree for high In content InGaN than low In content InGaN that is used in blue LEDs. The U.S. Pat. No. 8,138,493 solves this problem by providing a nanostructured LED device comprising InGaN quantum dots between a nanowire core and a nanowire shell that provide light emission in the infra-red to green wavelength region with improved emission. By way of example one such nanostructured LED device comprises a nanowire core made of GaN and InGaN quantum dots embedded in a GaN based shell.